There are some image forming apparatus to which a post-processing apparatus can be connected as an option to perform a post-process on sheets of paper outputted from the image forming apparatus, and an image forming system is constituted by equipping the image forming apparatus with the post-processing apparatus. Examples of the post-process includes stapling sheets of paper together, outputting sheets of paper onto a designated one of a plurality of paper output trays, and offsetting a position on a paper output tray in which sheets of paper are outputted.
Patent Document 1 discloses an arrangement of such an image forming system in which an image forming apparatus starts a second image formation job without waiting for a post-processing apparatus to complete preparation for change of post-processes and the post-processing apparatus starts a post-process for the second image formation job immediately after completing the preparation for change of post-processes.
That is, after the image forming apparatus suspends the conveyance of sheets of paper on completion of a first image formation job (i.e., the image formation job that came immediately before the second image formation job), the image forming apparatus resumes the feeding and conveyance of sheets of paper at an appropriate timing prior to the completion of the preparation for change of post-processes, and then supplies sheets of paper to the post-processing apparatus at substantially the same timing as the completion of the preparation for change of post-processes.
Thus, the amount of time required between the start of the first image formation job and the completion of the post-process for the second image formation job can be made smaller than ever before.
(Patent Document 1)
Japanese Unexamined Patent Application Publication No. 321482/2005 (Tokukai 2005-321482; published on Nov. 17, 2005)
However, although the arrangement of Patent Document 1 can prevent the image forming apparatus from undesirably waiting for the post-processing apparatus to complete preparation for change of post-processes, the arrangement of Patent Document 1 cannot make it possible to curb the decline in job efficiency that is attributed to the fact that in cases where the image forming apparatus performs image formation jobs in succession, the image forming apparatus delays the start of the next image formation job and waits in order to allow post-processing time for the previous image formation job.